1. Field of the Invention
The present invention generally relates to a starting arrangement for internal combustion engines. In particular, the present invention is an improved starter arrangement for such engines.
2. Description of Related Art
As is well known, many small internal combustion engine applications employ pull-type, or recoil, starters. With reference to FIGS. 7-9, such a starter arrangement will be introduced. Internal combustion engines with recoil starters have a dog cam arrangement in which a dog cam 200 engages a rotatable pulley 210 that is generally affixed to an end of an engine crankshaft. The rotatable pulley has a plurality of web portions that define a corresponding plurality of slots 212. The dog cam 200 is arranged to be pivoted about a shaft 206 and urged into an extended position by a clutch drive member 208 in a known manner.
As a starter cord is pulled, a starter drum, to which the dog cam 200 is attached, rotates and eventually a distal clasp portion 202 of the dog cam 200 engages a slot 212 in the pulley 210. The dog cam 200, thus, couples the starter drum and the pulley 210 together so long as the drum is spinning in the same direction as the pulley 210 and at the same rate. Thus, the two remain coupled until the rotational speed of the pulley exceeds the rotational speed of the drum. The pulley 210, meanwhile, exerts a compressive force on the engine by spinning the crankshaft. By spinning the crankshaft, the internal combustion cycle can be initiated as is known.
Once the engine has started, the pulley 210 will overrun the starter drum. So long as the operator is still rotating the starter drum via the starter rope, the clutch drive member 208 urges the dog cams 200 against the pulley 210. Thus, the clasp portion 202 of the dog cams 200 will bounce in and out of the slots 212 with which they were engaged while the engine was started. A ramping surface 204 that terminates in the clasp portion 202 amplifies the bouncing.
Previously, the ramping surfaces 206 and the clasp portions 202 of the prior dog cams 200 would temporarily clatter against the pulley 210 following an engine start. This condition would result because the pulley 210 was rotating faster under the power of the engine than the starter drum could rotate under the power of the starter cord. Additionally, if the starter drum was still rotating when the engine assumed operation under its own power, the dog cams 200 would remain engaged. Thus, the dog cams would repeatedly beat against the surfaces defining the slots 212 and cause unnecessarily high noise levels and possible undesirable engine component damage over time. The increased noise levels associated with the prior design are also undesirable, in part, due to the adverse impact of engine and vehicle noise on fish and wildlife.
Accordingly, one aspect of the present invention involves a recoil starter arrangement for an internal combustion engine. The recoil starter arrangement has a starter drum and a clutch drive member frictionally secured to the starter drum. A dog cam is pivotably secured to the starter drum in a location substantially adjacent to the clutch drive member. The dog cam has an external surface, a cam surface, and a ride surface which is interposed between the cam surface and the external surface. The ride surface defines a plane which is skewed relative to the external surface and the cam surface.
Another aspect of the present invention involves a recoil starter arrangement for an internal combustion engine. The recoil starter arrangement has a starter drum. A dog cam is attached to the starter drum by a shaft. The recoil starter arrangement also has a starter pulley. The starter pulley has an internal surface. The dog cam has a cam surface, an external surface and a ride surface interposed therebetween. A means is provided from engaging the dog cam with the starter pulley such that the ride surface of the dog cam selectively contacts the internal surface of the starter pulley.
A further aspect of the present invention involves a recoil starter arrangement for an internal combustion engine. The starter arrangement provides a starter pulley having a segmented inner surface defined at an inner radius. The segmented inner surface having slots defined therein. A dog cam member selectively contacts the segmented inner surface. The dog cam member also has a ride surface which is generally tangential to the inner radius while the dog cam member is in contact with the segmented inner surface.
Yet another aspect of the present invention provides an internal combustion engine having a recoil starting arrangement. The engine has an output shaft and a flywheel attached to the output shaft. A starter pulley is operably connected to the flywheel. The starter pulley has a plurality of engagement grooves separated by web portions. A dog cam is pivotably attached to a starter drum and has an engaging tip portion. The engaging tip portion is selectively engageable with one of the plurality of engagement grooves of the starter pulley. The engaging tip portion is desirably contoured to complement the web portions such that the engaging tip portion can substantially glide over the engaging grooves when the starter pulley rotates in a second direction relative to the starter drum. This arrangement, among others, can reduce a noise level associated with the starter arrangement following ignition.